fix(links): let CivitAI and HuggingFace links coexist (#1094)

A model could have CivitAI metadata and a HuggingFace link at the same time,
but only one of the two "View on ..." entries ever rendered, because both the
model modal and the card globe asked the `from_civitai` provenance flag which
source to show. `set_hf_url` wrote `false` and a CivitAI refresh wrote `true`,
so whichever ran last erased the other: linking HF hid "View on CivitAI" even
though the civitai payload was still in the sidecar, and (on the card) a later
refresh pointed the single globe icon back at CivitAI, hiding the HF entry.

Decide the links from the data itself instead:

- `set_hf_url` no longer touches `from_civitai`; it records where the metadata
  came from, and HF provenance is already tracked by `hf_url`.
- Add `hasCivitaiSource(civitai)` in the shared card/modal utils and gate the
  modal's CivitAI link, the card globe (title, enabled state, click target,
  new `data-has_civitai`) and the context-menu `civitai` action on actual
  CivitAI data (`modelId` / `model_id` / `id`). A dual-source model now shows
  both links, and a CivitAI-only model with no `hf_url` stays as before.
- Agent HF enrichment (`PostProcessor.is_hf_model`) keyed off
  `not from_civitai`, which stopped being a synonym for "has an HF source" once
  both sources can coexist (and already broke after a CivitAI refresh flipped
  the flag back to true). Key it off `hf_url` directly; the post-processor
  tests move to that discriminator and gain a dual-source case.

Regression tests: the set-hf-url handler preserves civitai + `from_civitai`
and no longer forces the flag false, the modal renders both links (including
with `from_civitai: false`), and the card globe targets/opens the right source
and is disabled when neither is available.

Backend: 2749 passed. Frontend: 1098 JS + 91 Vue tests passed.

static/js/components/shared/utils.js

@@ -36,6 +36,24 @@ export function formatFileSize(bytes) {
     return `${size.toFixed(1)} ${units[unitIndex]}`;
 }
 
+/**
+ * Whether a model has usable CivitAI metadata to link to.
+ *
+ * CivitAI links must be gated on the presence of actual CivitAI data rather
+ * than the `from_civitai` provenance flag: linking a model to HuggingFace used
+ * to flip `from_civitai` to false, which hid the CivitAI link even though the
+ * model still had CivitAI metadata. See issue #1094.
+ *
+ * @param {Object} [civitaiData] - The model's `civitai` payload
+ * @returns {boolean} True when a CivitAI model/version id is available
+ */
+export function hasCivitaiSource(civitaiData) {
+    if (!civitaiData || typeof civitaiData !== 'object') return false;
+    return Boolean(
+        civitaiData.modelId ?? civitaiData.model_id ?? civitaiData.id
+    );
+}
+
 /**
  * Render compact tags
  * @param {Array} tags - Array of tags